1. Field of the Invention
The present invention relates to storage containers. More particularly, the present invention relates to proppant discharge systems wherein proppant can be discharged from the storage container. Additionally, the present invention relates to a process for providing proppant to a well site by the transport and delivery of the proppant containers.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Hydraulic fracturing is the propagation of fractions in a rock layer caused by the presence of pressurized fluid. Hydraulic fractures may form naturally, in the case of veins or dikes, or may be man-made in order to release petroleum, natural gas, coal seam gas, or other substances for extraction. Fracturing is done from a wellbore drilled into reservoir rock formations. The energy from the injection of a highly-pressurized fracking fluid creates new channels in the rock which can increase the extraction rates and ultimate recovery of fossil fuels. The fracture width is typically maintained after the injection by introducing a proppant into the injected fluid. Proppant is a material, such as grains of sand, ceramic, or other particulates, that prevent the fractures from closing when the injection is stopped.
With the rise of hydraulic fracturing over the past decade, there is a steep climb in proppant demand. Global supplies are currently tight. The number of proppant suppliers worldwide has increased since 2000 from a handful to well over fifty sand, ceramic proppant and resin-coat producers.
By the far the dominant proppant is silica sand, made up of ancient weathered quartz, the most common mineral in the Earth's continental crust. Unlike common sand, which often feels gritty when rubbed between the fingers, sand used as a proppant tends to roll to the touch as a result of its round, spherical shape and tightly-graded particle distribution. Sand quality is a function of both deposit and processing. Grain size is critical, as any given proppant must reliably fall within certain mesh ranges, subject to downhole conditions and completion design. Generally, coarser proppant allows the higher flow capacity due to the larger pore spaces between grains. However, it may break down or crush more readily under stress due to the relatively fewer grain-to-grain contact points to bear the stress often incurred in deep oil- and gas-bearing formations.
Typically, in any hydraulic fracturing operation, a large amount of such proppant is required. Typically, it has been difficult to effectively store the proppant at the fracturing sites. Additionally, it has been found to be rather difficult to effectively transport the proppant to the desired location. Often, proppant is hauled to the desired locations on the back of trucks and is dumped onsite. Under such circumstances, the proppant is often exposed to adverse weather conditions. This will effectively degrade the quality of the proppant during its storage. Additionally, the maintenance of proppant in containers at the hydraulic fracturing site requires a large capital investment in storage facilities. Typically, the unloading of such storage facilities is carried out on a facility-by-facility basis. As such, there is a need to be able to effectively transport the proppant to and store the proppant in a desired location adjacent to the hydraulic fracturing location.
U.S. patent application Ser. No. 13/427,140, filed on Mar. 22, 2012 by the present inventor, describes a system of the delivery of proppant between a loading station and the well site. This application describes the steps of placing the storage container in a location adjacent to a train site such that the proppant, as delivered by the train, can be discharged into the container. The container can then be transported for storage in stacks at the loading area or can be delivered to a tilting mechanism at the loading station. The tilting station will tilt the container so as to allow the proppant to flow outwardly therefrom. This proppant will flow, by a conveyor, to a pneumatic truck. The truck can then transport the proppant over the highways to the well site. At the well site, the proppant from the pneumatic truck can then be discharged into a twenty foot container at the well site. These twenty foot containers can be stored at the well site in a stacked configuration. Ultimately, each of the containers can be transported to another tilting mechanism at the well site so that the proppant within each of the storage container can be discharged onto a conveyor and ultimately for use during the fracturing operation.
One of the problems with this system is that each of the containers is handled by various types of equipment and at multiple times. Ultimately, heavy-duty equipment is required to move a twenty foot container that is filled with proppant from one location to another. This heavy-duty equipment can be extremely expensive. Additionally, since the container, along with the proppant therein, is subject to repeated handling, there is a possibility of degradation of the proppant within the container. Ultimately, every time the proppant is loaded, discharged, loaded again, and then discharged, it is subject to wear-and-tear and degradation. As such, a need has developed so as to avoid the multiple handlings of the proppant and the proppant storage container.
In normal use, a twenty foot container can hold 96,000 pounds of proppant. However, weight limits imposed on trucks by highway authorities limit the amount of weight that can be carried to 48,000 pounds. As such, in order to comply with the law, it is only possible to pour approximately 45,000 pounds of proppant into the container. This only partially fills the container and leaves a great deal of wasted space within the container. As such, it has been felt to be impractical to utilize transported containers to move the proppant from the loading station directly to the well site.
Whenever a twenty foot container is loaded with proppant, the proppant tends to pile up in a pyramid shape. As such, there is a great deal of wasted space within the container. If the container is not tilted at a rakish angle, there will always remain a certain quantity of proppant that remains within the container. It was not felt possible to place an outlet at the floor of the container since such an outlet on a twenty foot container would be ineffective in allowing the proppant to be discharged fully from the interior of such a container.
Demurrage is continual problem for well-site operators. Demurrage is the charge, by the trucking companies, of having the truck in a position waiting for loading or discharging. In other words, demurrage covers the idle time associated with a truck on a particular project. If trucks were used so as to move the twenty foot container from the loading station at a drill site, each of the trucks would have to wait until the proppant was required at the drill site. At that time, the container can be removed from the truck and positioned so as to be discharged. Ultimately, the truck would have to wait until the container was fully discharged before it could take the empty container back to the loading station. This waiting time significantly increases the cost of demurrage to the well-site operators. Additionally, and furthermore, as the containers are being loaded at the loading station, each of the trucks will have to wait in order to receive a particular load. As such, it is often felt possible to properly use the typical twenty foot storage containers for proppant delivery and storage.
In the past, various patents have issued relating to storage and transport facilities. For example, U.S. Patent Publication No. 2008/0179054, published on Jul. 31, 2008 to McGough et al., shows a bulk material storage and transportation system. In particular, the storage system is mounted on the trailer of a truck. The storage system includes walls that define an interior volume suitable for receiving the aggregate material therein. There are hoppers provided at the bottom of the container. These hoppers have inclined walls. The hoppers can extend so as to allow the material from the inside of the container to be properly conveyed to a location exterior of the container. Actuators are used so as to expand and collapse the container.
U.S. Pat. No. 7,240,681, issued on Jul. 10, 2007 to L. Saik, describes a trailer-mounted mobile apparatus for dewatering and recovering formation sand. The trailer is mounted to a truck-towable trailer so as to receive sand therein. The container has a pair of sloping end walls. The back end of the container is suitably openable so as to allow the sand to be removed therefrom. A pneumatic or hydraulic ram is provided on the forward part of the container so as to allow the container to be lifted angularly upwardly so as to allow sand to be discharged through the gate at the rear of the container.
U.S. Pat. No. 4,247,228, issued on Jan. 27, 1981 to Gray et al., describes a dump truck or trailer with a pneumatic conveyor. The container is mounted to a frame on wheels. A hydraulic ram tilts the container for dumping through a rear outlet. A pneumatic conveyor is carried by the frame with an intake at the rear of the container. A gate allows the solids to be dumped conventionally by gravity or to be blown to a storage facility by the pneumatic container. The container has a top hatch formed therein so as to allow the solids to be introduced into the interior of the container.
U.S. Pat. No. 2,865,521, issued on Dec. 23, 1958 to Fisher et al., shows a bulk material truck that has an interior volume suitable for the receipt of bulk material therein. A pneumatic conveyer is utilized so as to allow the removal of such material from the bottom of the container. A pair of sloping walls are provided on opposite sides of the container so as to allow the bulk material within the container to be passed toward the bottom of the container. A top hatch is provided on the top of the conveyer. The pneumatic conveyer is connected to the bottom of the container.
It is an object of the present invention to provide a proppant storage container that allows proppant to be easily transported and stored.
It is another object of the present invention to provide a proppant storage container that allows the proppant to be easily and efficiently discharged to the bottom of the container.
It is another object of the present invention to provide a proppant storage container which allows for the effective storage of proppant at the fracturing site.
It is another object of the present invention to provide a process for delivering proppants that eliminates the use of pneumatic trailers.
It is further object of the present invention to provide a proppant storage container and a process for delivering proppant in which of the containers can be moved by a simple forklift.
It is another object of the present invention to provide a process for delivering proppants which effectively eliminates demurrage associated with the loading station and at the well site.
It is a further object of the present invention to provide a process of the deliver proppant which avoids the degradation of the proppant as a result of repeated handling.
It is a further object of the present invention to provide a proppant discharge system which provides a premeasured amount of proppant to the drill site.
It is still another object of the present invention to provide a proppant container which satisfies highway regulation and which has less void space within the interior of the container.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.